2 different `Dialect` types - one in `csv` module and other in `_csv` module

Consider this code:

from csv import get_dialect


def foo(s: str):
    dialect = get_dialect(s)
    reveal_type(dialect)

mypy reports

dialects.py:6: note: Revealed type is "_csv.Dialect"

One would expect the result would be csv.Dialect.

There are 2 classes called Dialect in typeshed:
https://github.com/python/typeshed/blob/2480d7e7c74493a024eaf254c5d2c6f452c80ee2/stdlib/_csv.pyi#L28
and
https://github.com/python/typeshed/blob/2480d7e7c74493a024eaf254c5d2c6f452c80ee2/stdlib/csv.pyi#L61

get_dialect() is imported in csv.pyi from _csv.pyi, so the declaration in _csv.pyi is returning _csv.Dialect instead of csv.Dialect, so the type checkers see that as 2 separate classes.

まず stdlib/_csv.pyi と stdlib/csv.pyi を比較し、インポートされた get_dialect 宣言と 2 つの Dialect クラスに注目してください。再現用の mypy スニペットを実行し、reveal_type が _csv.Dialect ではなく csv.Dialect を報告することを確認してください。